Excitonic effects in oxyhalide scintillating host compounds
- School of Engineering Sciences and Technology (SEST), University of Hyderabad, Prof. C. R. Rao Road, Gachibowli, Hyderabad 500 046, Telangana (India)
Ab-initio calculations based on density functional theory have been performed to study the electronic, optical, mechanical, and vibrational properties of scintillator host compounds YOX (X = F, Cl, Br, and I). Semiempirical dispersion correction schemes are used to find the effect of van der Waals forces on these layered compounds and we found this effect to be negligible except for YOBr. Calculations of phonons and elastic constants showed that all the compounds studied here are both dynamically and mechanically stable. YOF and YOI are found to be indirect band gap insulators while YOCl and YOBr are direct band gap insulators. The band gap is found to decrease as we move from fluorine to iodine, while the calculated refractive index shows the opposite trend. As the band gap decreases on going down the periodic table from YOF to YOI, the luminescence increases. The excitonic binding energy calculated, within the effective mass approximation, is found to be more for YOF than the remaining compounds, suggesting that the excitonic effect to be more in YOF than the other compounds. The optical properties are calculated within the Time-Dependent Density Functional Theory (TDDFT) and compared with results obtained within the random phase approximation. The TDDFT calculations, using the newly developed bootstrap exchange-correlation kernel, showed significant excitonic effects in all the compounds studied here.
- OSTI ID:
- 22305745
- Journal Information:
- Journal of Applied Physics, Vol. 116, Issue 13; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Publisher:
- American Institute of Physics (AIP)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BINDING ENERGY
BROMINE COMPOUNDS
CHLORINE COMPOUNDS
CORRELATIONS
DENSITY FUNCTIONAL METHOD
DISPERSIONS
EFFECTIVE MASS
FLUORINE COMPOUNDS
IODINE COMPOUNDS
LUMINESCENCE
OXYGEN COMPOUNDS
OXYHALIDES
PHONONS
RANDOM PHASE APPROXIMATION
REFRACTIVE INDEX
TIME DEPENDENCE
VAN DER WAALS FORCES
YTTRIUM COMPOUNDS